Radio drift course finder



July 16, 1940. M F, BATES 2,207,709

RADIO DRIFT COURSE FINDER Filed Dec. 15, 1935 4 Sheets-Sheet l llll/ll/l/IIII.

INVENTOR gm/Msn F nns Mft/M H16 ATT`ORNEY.

July 16, 1940. M, F, BATES 2,297,709

RADIO DRIFT COURSE FINDER Filed Dec. 13, 1935 4 Sheets-Sheet 2 51g: 4': 51g: 5l-

78 4 E; 85 75 /0 5 3 ia-:

l aa 84 4 37 "'57 INVENTOR NcRr/Men nf H15 A'roRNEY July 16, 1940. M. F. BATES 2,207,709

RADIO DRIFT COURSE FINDER Filed Dec. 13, 1935 4 Sheets-Sheet 5 INVENTOR @gm/MER fnfs MATT'ORNEY. 3

July 16, 1940. M. F. BATES RADIO DRIFT COURSE FINDER Filed Dec. l5, 1935 4 Sheets-Sheet 4 l l l /l/l/l/l/l/l NVENTOR gonnnfnf.' nss ATTORNEY ffatented July 16, 1940 i PATENT RADIO Dam coURsE FINDER Mortimer F. Bates, Brooklyn, N. Y., assigner to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York .Application December 13, 1935, Serial No. 54,196

This invention relates, generally, to direction Finding and the invention has reference, more oarticularly, to a novel radio drift course nder adapted for use on dirigible craft, such as airilanes, ships, etc., whereby the craft may be :teered toward a radio sending station in a `=traight ground track.

Heretofore, it has been diflicult or impossible :o steer a craft directly and by the shortest posfible route to a desired object or destinationv then such destination is indicated solely by an -rdinary radio broadcasting station, i. e., a staion not providing a directional beam, and when i cross current and/or wind exists, tending to irive the craft from its course. Ordinarily, in he presence of such a cross current and/ or wind be craft will be steered so as to travel along a :urved path that may be manylmiles longer than `ine direct course to the desired object or destinaon The principal object of the present invention s to provide a novel radio drift course inder hat is easily manipulated to provide for the yteering of the craft quickly and smoothly onto uch heading that the craft will thereafter mainain a substantially straight and hence the shortfst possible course to the desired destination, rnd without the necessity, in'the absence of a harige in the magnitude or direction of the cross urrent and/or wind,` of changing course as the raft proceeds.

Another object of the present invention lies n the provisionA of a novel radioV drift course nder of the above character that is adapted for se in conjunction with an automatic pilot such 1s that disclosed in my prior patent, joint with filmer A. Sperry, Jr., and Bert G. Carlson, No. 992,970; the said drift course finder operating hrough the automatic pilot to obtain in one\` mooth operation a true ground track to or from n. radio station, and without knowledge on the art of the pilot of the force and direction of he Wind.

Other objects and advantages will become apiarent from the speciilcation, taken in connect ion with the accompanying drawings wherein he invention is embodied in concrete form.

In the drawings,

Fig. 1 is. a diagrammatic view illustrating a yplcal installation of one form of the novel adio drift course finger of this invention, which 'mn of the invention employs manually operable `ieans for adjusting the loop antenna of the evice in azimuth.

Fig. 2 is a view in front elevation of the radio 19 Claims. (Cl. 172-282) compass indicator employed in the radio drift course nder.

Fig. 3 is a fragmentary, part sectional View of a variable speed mechanism employed in the novel radio drift course finder of this invention. d

Fig. 4 is a somewhat modifled arrangement showing a fragmentary sectional view of a somewhat diflerent type of variable speed mechanism.

Fig. 5 is a view in front elevation of the structure of Fig. 4.

Fig. 6 is a diagrammatic View of a somewhat modiied form of the invention, wherein power means is employed for adjusting the loop antenna in azimuth and wherein control means are operated from the radio compass indicator for w maintaining the craft on a determined drift course.

Fig. '7 illustrates an electrical picirHci from the compass indicator employed in the arrangement of- Fig. 6.

Fig. 8 is a sectional view taken along line 'li-8 of Fig. 7.

Fig. 9 is a fragmentary sectional View of the automatic pilot course setting and follow-up mechanism. l 25 Fig. v10 is an enlarged sectional View taken along line Ill- I0 of Fig. 7.

Fig.` 1.1 is a sectional view of another of electrical pick-off from the compass indicator and adapted for use in the arrangement oi Fig. 6.

Fig. 12 is an enlarged sectional View taken along line |2-I2 of Fig. 11.

Fig.v 13 is a sectional View taken along line lil-I3 of Fig. 12.

Fig. I4 is a diagram illustrating the action of 35 the radio drift course iinder in bringing a craft onto a desired drift course.

Similar characters of reference are used in all of the above views to indicate corresponding parts.

Referring now to Figs. 1l to 3 of the the reference numeral l designates the instrument board view of `an automatic pilot having 'a directional gyro 2 and an artificial horizon t, the said automatic pilot being preferably of the type disclosed in my prior mentioned patent. An Y electric servo-motor is connected through suit- Ais controlled, whereas by actuating buttons Si the operation of motor d in the reverse direction is controlled. Motor t, when running, serres to turn the course setting knob 6 in the direction determined by the direction of running of motor A, whereby the course of the craft is changed at a relatively slow, uniform, desired rate of preferably 1 to 1%" per second in the desired direction, determined by whichever pair of buttons 8 or 9 are actuated.

Motor 4 is also connected through transmission means i9 to one gear II of a differential i2, the opposing gear II of which differential is adapted to be driven from a crank I3 acting through gearing I4. The arm I5 of differential I2 operates through step-up gearing I9 to rotate an indicator disc I1. Disc I1 is preferably colored radially in contrasting colors, whereby the moment at which the same comes to rest can be easily detected. Crank I3 also acts through gearing I4 and fiy wheel i3" to drive transmission shafting I8 connected for turning an antenna loop I9. 'Ihe angular position of the loop I9 is preferably indicated by turnable dial 25 connected to loop I9, the movement of dial 25 being indicated by reference to a stationary pointer 26. l

Antenna loop I 9 and a non-directional antenna 29 are connected to a suitable receiving unit 2l for actuating a suitable radio directon indicator or homing device 24. Such radio direction or compass indicators 24 are known in the art and usually employ a polarized indicator in which the indication varies with the phase relationship of the signals received from the two antennae. Receiver 2| is shown as having a tuning dial 22 and binaural ear phones 23. Radio direction or compass indicator 24 is shown as mounted o-n panel 1 With loop I9 set in its zero position, i. e., with the plane of this loop I9 extending at right angles to the -longitudinal or fore and aft axis of the craft, if the craft is headed directly toward a radio transmitting. station, the radio compass indicator 24 will read Zero, Whereas if the craft is headed o to the right of the station, for eX-v ample, the pointer 21 will turn toward the indicia R on dial 28, showingthat the craft must be turned toward the left to again head toward the station.

In use, assume that the craft is in a cross current or wind of unknown velocity and direction and that it is desired to place the craft on that heading which will bring the same by the shortest route, i. e., by a straight ground track, to any desired radio transmitting station, such as a broadcasting station. To accomplish this, the loop I9 is first set in its zero position, i. e., with its plane extending at right angles to the longitudinal axis of the craft. If loop I9 is not initially in its zero position it may be 4brought to this position by turning crank I3. The desired station is then tuned in on dial 22 and the course changed by turning knob 6, if necessary, until the radio direction indicator 24 reads zero at the moment, thereby indicating that the craft is heading momentarily directly toward the radio station, corresponding to position A ofFig. 14. .This course is. then held by means of fthe automatic pilot I and, owing 'to the cross current or wind gv, Jthe radio compass meter 29 will soon show rif u Thus, with the wind in the ,direction shown in Fig, 14, the drift is to the right of the straight course to station T. The properbutton 8 onlpanel 1 is then pressed for causing motor 4 to operate and turn the. course setting knob 6, whereby the craft is started to turnfat a slow* uniform .rate of about 1 per second toward the left, i, e., in the direction to correct for the drift. The motor 4 also operates through transmission means I0 to drive gear II of differential I2 so that arm I5 is rotated and acts through step-up gearing I6 to turn indicator disc I1 at a fairly high rate of speed. The operator now turns crank I3 so as to keep the reading of the compass indicator 24.at zero, i. e., by turning crank I3 in the proper direction and. speed this crank I3 acts through gearing Id and transmission means I8 to turn loop I9 so that the axis of this loop remains on the station. By referring to Fig. 14it will be noted that While the craft is turning toward the left, the loop I9 is. turning toward the right with respect to the craft. At rst, i. e., when the craft rst starts to turn, the crank I3 need be turned but slowly to keep the indication of meter 24 at zero, but as the turn continues, the rate ofA turning of crank I3 must increase in order to keep the meter at zero. As the crank I3 is turned, gearing I 4 drives gear ii' of differential I2 in the direction opposite to that of gear II, thereby tending to slow up the speed of disc I1. As the speed of crank I3 and hence that of loop I`9 increases, a point is nally reached when the rate of turning of loop I9 toward the right is equal and opposite to the rate of turning of the craft toward the left, at which mo'rnent the indicating disc I1 will come to rest, since at that instant both sides of differential i2 are being driven at the saine speed in opposite directions, and the operator immediately operates the proper` button 8 to stop the turning of the craft.4 When the disc I1 thus comes to rest, the loop I9 is rotationally standing still in space, thereby indicating that the craft lis at A' on a drift course which, if maintained by keeping the craft on its present heading and at the drift angle lX, will lead the craft directly to the station T over a straight ground course 39.

If the novel radio drift course finder of this invention were not used, the craft would travel along the curve 3| in Fig. 14. Actual ying conditions are exaggerated in this figure for the sake of clearness. Thus, in practice the distance A tolA during which the craft is arriving at a -straight ground track is much shorter'than that .shown in the gure, so that course 36 substantially coincides with the straight lin'e AT, Whereas course 3| would be miles to the right of line AT.

In the slightly modified arrangement shown in Figs. 4: and 5, the antenna loop I9 of Fig. 1 is power driven and the crank I3' (corresponding to crank i t) is a rate setting means for determining the rate at which the loop I9 will be turned. Thus, in Figs. 4 and v5, the transmission means III, driven from motor 4, rotates a drive disc',32 that in turn drives a friction disc 33. Friction disc 33 is splined for longitudinal movementj'on a shaft 3e that is connected for turning the antenna loop I9. The hub 35 of friction disc 33- is grooved and connected by a yoke 36 to a nut .'31 on is mounteabehind the window 44'. y

In usingthis form of the invention, when the motor li ((Fig. 1) is started, theI transmission means I0 rotates drives disc 32 while at the same time motor 4 acts through the automatic pilot to turn the craft at the desired slow rate of about l 2,207,709 '1'or 11/2 per second. Friction disc 33 at the beginning of the turn is at the center of the drive vdisc 32 and the ,crank I3 is now turned to advance disc 33 over disc 32 so as to keep the reading ,of compass 24 zero, the shaft 34 for turning'the loop I9 being rotated at a gradually increasing rate due to the operation of crank I3. When the speed of turning of loop |9 with respect to the craft is equal to that of the craft in azimuth but in the opposite direction, the arm 39 will have reached bell crank lever 40 and turned the same 'so that indicator 4| is moved down so as to be visible through the window 44, thereby indicating to the operator that motor 4 should be immediately stopped as the craft is on the proper drift course. n

In the form of the invention shown in Figs. 6

to 10, automatic means is provided for arresting the turning of the craft when the proper drift angle is reached, together with means for making the automatic rudder control subject thereafter to correction by the radio compass indicator. The radio compass indicator 24 of Fig. 6 is shown in detail in Figs. 7 and 8. In these figures the moving coil 45 of the radio compass, instead of being supported in jewel bearings, is carried by a statically balanced air borne member 46 provided with a rearwardly directed air nozzle 41. Member 46 and its supporting bearing 48 are provided with cooperating hemispherical surfaces for maintaining the supporting air film, each of these members having one convex and one concave surface so disposed that all air eddies are deflected toward the rear of the instrument and away from the sensitive meter element 45.

Positioned rearwardly and to the sides of the air nozzle 41 are two independently movable paddles and 50' that are pivoted upon nuts 5|` Casing 58 is arranged to have air withdrawn.

therefrom through a pipe 59 as by connection to a vacuum pump or Venturi tube, thereby causing atmospheric air to enter passage 60 in bearing 48 to support the member 46 and coil 45 in a substantially frictionless manner. 'I'his air dischargedffrom nozzle 41 passes between paddles 50' and 50' (see Fig. 8) without deflecting these paddles so long as the compass indicator 24' reads zero. As soon as th-e compass indicator moves off the zero position, nozzle 41 is likewise moved so as to direct the air' against one of the paddles 50 and 50 depending upon the direction of turning of the compass indicator moving coil 45. With the air thus blowing against one of the paddles, its spring 53 isdeected and the paddle turned back so that its movable contact is caused to engage the cooperating stationary contact, thereby completing a circuit under the the uid support from member 46 periodically, to cause periodic arresting of member 46. A butterily valve 63 is positioned in the passage leading to air outlet pipe 59, which valve has its stem 64 (Figs. '1 and 10) intermittently turned by a Geneva gear 65 that is driven from a small turboflywheel 66 through worm and wheel reduction gearing 61. Turbo-flywheel 66 is `driven by an air jet supplied through a pipe 68 connected to the atmosphere, suction from pipe 59 exerted through a port 69 serving to cause the jet to operate. Preferably, the valve drive is such that the iiuid support for member 46 is withdrawn for a period of one half second at one half second intervals, which is sulcient to make the device practically dead beat.

Referring new to Fig. 6, Y1li) is'thefchan'ge course f dial of the automatic pilot directional gyro 2, the said dial being adapted to be turned from course setting knob 6 through shafting 1| and gearing 12 (see also Fig. 9). A friction mounted bevel gear 13 is adapted to be driven from a mating gear 14 that in turn is driven from the reversible servo-motor 4' through reduction gearing and a flexible shaft 15. Parts I9, I3', 32, 33, 34, 35 and 38 are similar to corresponding parts of Figs. 4and 5 and hence are correspondingly numbered. Nut 31 on shaft 38 has a forked end 16 Ifor actuating a double throw switch 11 to its open, and the loop I9 is set at zero by turning crank 18 if necessary. The craft is then headed directly for the desired station by turning knob 6 till compass indicator 24' reads zero. The indicator 24 will thereafter soon indicate drift due to the cross current or wind and the proper button 19 or 19 of double throw switch 11 is actuated to operate motor 4' in the proper direction to turn the change course dial 10 and hence the craft ata steady rate of about 1 per second to correct for drift. Spring pressed lever 88, by entering one of the notches 8| or 8|', serves to retain switch 11 in its engaged position. Crank I3' is turned to advance friction disc 33 over drive disc 32 so as-to turn loop |9 and maintain indicator 24 at zero. Just as the craft and loop I9 are `turning at the same rate in opposite directions, i. e., with loop |9 stationary in space, the forked end 16 of nut 31 will engage switch 11 and center the same in the o position, thereby stopping motor 4' with the craft headed on the proper drift course. The operator now runs the nut 31' back so that the friction disc 33 is at the center of drive disc 32, at which time an arm 82 on nut 31' will close contacts 83, thereby preparing the circuit through common lead 84 so that the paddle actuated contacts 55, 56 and 55', 56 of meter 24' (see Figs. 7 and 8) are thereafter effective to automatically control motor 4' when small deviations from the true drift course are indicated by the compass indicator 24', the indicator 24 thusly serving to hold the craft on the correct drift course. In Fig. 6, 85 designates the craft rudder, and flexible connector 86 and gearing 81 the rudder follow-up to the automatic pilot.

Figs. 11 to 13 show a somewhat modified form of electrical pick-oil.' from the radio compass inair borne member 81 supported from hemispherical end bearings 88. Air for supporting member 8l and for nozzle 91' is supplied through screen and passage 9|. Nozzle itl directs air be-= tween two paddles 92 and 92 pivoted at 93 and '93' and carrying projections 94 and 94 for closing the open upper ends of pipes and 95.

The air pressure from pipes 95 and 95' is transmitted to opposite sides of a piston or flexible diaphragm 96, which divides into two partsY the interior space within the housing 91. Air is continuously withdrawn from both sides of the diaphragm through apertures l00 and |00 connected to the common exhaust pipe l0! leading to a venturi or pump.

In use, when the craft moves olf Vthe set drift course, the nozzle l' is tilted so as to direct air against one of the paddles 92, 92 depending on the direction of the deviation, thereby causing such paddle to swing up so that its projection 94 or 94 swings down to close the top of the corresponding pipe 95 or 95', whereby the pressure in the pipe thus closed drops, causing diaphragm 96 to move to the right or left, carrying with it stem 02 secured thereto and effecting engagement of movable contact ID3 with one of the stationary contacts |94 or lli' connected to leads 51 and 5l' leading to motor 4', thereby effecting the desired operation of this motor.

As many changes could be made in the above construction and many apparently Widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. v

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In combination with a craft, of course changing means therefor, and a radio drift course finder including a motor connected for setting said course changing means, a turnable directional antenna, means for turning said antenna to maintain the same parallel to a wave front, and means responsive to the relative speeds of turning of said antenna with respect to the craft and o-f the craft in azimuth and operable at the moment those speeds are the same, but in opposite directions, to stop the turning of the craft.

2. In a radio drift course finder for dirigible craft, means for causing the craft to4 turn in azimuth at a predetermined rate toward the proper drift course, a directional antenna, means for turning said antenna to hold the same on a desired broadcasting station while so turning the craft, and means responsive to the relative turning speeds of the craft in azimuth and of said antenna with respect to the craft for determining the time to stop the turning of the craft, said time obtaining at the moment said antenna is angularly stationary in space.

3. In a radio drift course finder for dirigible craft, means for causing the craft to turn in azimuth at a predetermined rate toward the proper drift course, a directional antenna, means for turning said antenna tol hold the same on a desired broadcasting station while so turning the craft, means responsive to the relative turning speeds of the craft in azimuth and of said antenna with respect to the craft for determining the time to stop the turning of the craft, said time obtaining at the moment said antenna is angularly stationary in space, and means for holding the craft on the desired drift course, said last named means being responsive to change in the electrical output of said directional antenna.

4. In a radio drift course nderfor dirigible craft, means for causing the craft to turn in azimuth at a predetermined rate toward the proper drift course, a turnable directional antenna, a radio compass responsive to the electrical output of said antenna, means for so turning said antenna whereby said radio compass may be caused to remain at zero position during turning of the craft, and means responsive to the relative turning speeds of said antenna with respect to the craft and of the craft in azimuth and operable at the moment said antenna is angularly stationary in space for indicating the time to stop thewturning of the craft. Y Y

5. In a radio drift course finder for dirigible craft, means for causing the craft to turnin azimuth at a predetermined rate toward the proper drift course, a turnable directional an tenn, a radio compass responsive to the electrical output of said antenna, means for so turning said antenna whereby said radio compass may be caused to remain at zero position during turning of the craft, and means responsive to the relative turning speeds of said antenna with respect to the craft and of the craft in azimuth and operable at the moment said antenna is angularly stationary in space to stop the turning of the craft.

6. In a radio drift course nder for dirigible craft, a turnable directional antenna, a radio compass responsive to the electrical output of said antenna, transmission means for turning said antenna whereby said radio compass may be caused to remain at zero position during the turning of the craft toward a drift course, an indicator, gearing connected to said indicator and operated rin response to the relative turning movements of said antenna with respect to the craft and of the craft in azimuth, whereby said indicator is caused to show when said antenna is angularly stationary in space.

7. In a radio drift course finder for dirigible craft having steering means, a turnable directional antenna, a compass indicator operated in response to the output of said antenna, a reversible motor for controlling said steering means, manually operable means for turning said antenna, differential gearing driven from said motor and from said manually operable means, and usable in conjunction with said compass indicator, for indicating when said directional antenna is angularly stationary in space so that said motor may be stopped with the craft on a desired drift course.

8. In a radio drift course finder for dirigible craft having steering means, a turnable directional antenna, a compass indicator operated in response to the output of said antenna, a reversible motor for controlling said steering means, and for turning said directional antenna, control means for determining the rate of turning nf said directional antenna, whereby said compass indicator is not deflected, and indicator means operated from said control means for showing when said directional antenna is angularly stationary in space.

9. In a radio drift course finder for dirigible craft having steering means, a turnable directional antenna, a compass indicator operated in response to the output of said antenna, a reversible motor for controlling said steering means and for turning said directional antenna, control means for determining lthe rate of turning of said directional antenna, whereby said compass indicator is not deflected, and switch means ,operated from said control means when said directional antenna is stationary inspace to effect the stopping of said motor.

10. In a radio drift course finder for dirigibleA craft having steering means, a turnable directional antenna, a compass indicator operated in respo-nse to the output of said antenna, a reversible motor for controlling said steering means and for turning said directional antenna, control means for Vdetermining the rate of turning of said directional antenna, whereby said compass indicator is not deflected, switch means operated from said control means when said di-l a reversing pick-off from said radio compass indicator for causing said motor means to operate in either direction.

12. In a gyro pilot with homing radio control, a directional antenna, a course maintaining gyro, motor means for turning said directional antenna and for setting the course from said gyro, a radio compass indicator responsive to the electrical output of said directional antenna, and a pick-off from said radio compass indicator for controlling said motor means, said pick-off comprising an air nozzle movable by the movable element of said radio compass indicator, and electrical contact controlling paddles selectively actuated by air from said air nozzle.

- 13. In a gyro pilot with homing radio control, a directional antenna, a course maintaining gyromotor means fo-r turning said directional antenna and for setting the course from said gyro, a radio compass indicator responsive to the electrical output of said directional antenna, and a pickoif from said radio compass indicator for controlling said motor means, said pick-ofi comprising an air borne air nozzle movable by the movable element `of said radio compass, means for damping the movements of said nozzle, paddles selectively actuated by said air nozzle, and contacts in the circuit of said motor controlled by said paddles.

14. In an automatic steering gear for aircraft, a radio drift course finder including means for causing the craft to turn at a predetermined slow rate, a turnable directional antenna, means for turning said antenna to maintain the same parallel to a wave front, and means responsive to the relative speed of turning of said antenna with respectto the craft and of, the craft in azimuth for determining the time of stopping of said first named turn causing means, whereby the craft is brought on a straight ground course toward the sending station.`

15. In a gyro pilot with homing radio control, a directional antenna, a course maintaining gyro, motor means for turning said directional antenna and for setting the course from said gyro, a radio compass indicator responsive to the electrical output of said directional antenna showing left and right deviations from course, a pneumatic pick-off from said radio compass indicator, and electric contacts operated thereby for controlling said motor means.

16. As a means for actuating a power motor from a sensitive indicator, an air borne member actuated by a. movable element of said indicator, an air nozzle carried thereby, means for causing air flow for floating said member on an air film and for issuing air from said nozzle, spaced biased paddles or vanes adjacent said nozzle and adapted to be moved by the air jet therefrom on displacement of said indicator, and reversing electrical contacts operated directly or indirectly by the displacement of said paddles for operating said motor.

17. A pick-off attachment for sensitive indicators for controlling a power servo motor, comprising the combination with the sensitive element, an air bearing member coupled thereto for rotation therewith, spherical type air bearings for floating said member for rotation about the axis of said indicator, means for maintaining a` differential air pressure within and without said bearing-to oat said member on a film of owing air, said member also having an eccentric aperture through which some of said air flow escapes, a pair of biased pivoted vanes adjacent said aperture and adapted to be displaced by the jet issuing therefrom upon movement of said aperture, and differential power means controlled by the relative movement of said vanes for controlling said servo motor.

18. In a radio homing attachment for an automatic pilot for aircraft, the combination with a radio compass indicator of an air borne member connected with the movable element thereof, an air nozzle carried by said member, means for causing air flow for floating said member on an air film and for issuing from said nozzle, a biased pivoted vane adjacent said nozzle and adapted to be moved by the jet therefrom upon displacement of said indicator, and power means controlled by the movement of said vane for altering the course steered by said automatic pilot.

19. In an automatic pilot forcraft with homing radio control, a radio directional loop rotatably mounted on the craft, means for causing turning of the craft through the automatic pilot,

' means for turning said loop to maintain it on the 

